If $x \circledcirc y = 3x-3$ and $x \bigtriangleup y = x+3y$, find $5 \bigtriangleup (-2 \circledcirc -6)$.
First, find $-2 \circledcirc -6$ $ -2 \circledcirc -6 = (3)(-2)-3$ $ \hphantom{-2 \circledcirc -6} = -9$ Now, find $5 \bigtriangleup -9$ $ 5 \bigtriangleup -9 = 5+(3)(-9)$ $ \hphantom{5 \bigtriangleup -9} = -22$.